Below are the currently identified optimizations that sstan identifies. If you would like to check out a list of patterns that are ready to be implemented and you would like to add them to the repo, you can check out the Contribution.md!
| Optimization | Description |
|---|---|
| address_balance | Use selfbalance() instead of address(this).balance. |
| address_zero | Use assembly to check for address(0). |
| assign_update_array_value | When updating a value in an array with arithmetic, using array[index] += amount is cheaper than array[index] = array[index] + amount. This optimization also catches other arithmetic, bitwise and other operations. |
| bool_equals_bool | Instead of if (x == bool), use if(x) or when applicable, use assembly with iszero(iszero(x)). |
| cache_array_length | Cache array length during for loops. |
| cache_storage_in_memory | Cache Storage Variables in Memory |
| constant_variables | Mark storage variables as constant if they never change and are not marked as constants. |
| event_indexing | Event is not properly indexed. |
| immutable_variables | Mark storage variables as immutable if variables are assigned during deployment and never change afterwards. |
| increment_decrement | Use unchecked{++i} instead of i++, or ++i (or use assembly when applicable). This also applies to decrementing as well. |
| memory_to_calldata | Use calldata for function arguments marked as memory that do not get mutated. |
| multiple_require | Use multiple require() statements instead of require(expression && expression && ...). |
| optimal_comparison | Use strict > & < operators over >= & <= operators. |
| pack_storage_variables | Tightly pack storage variables for efficient contract storage. |
| pack_struct_variables | Tightly pack struct variables for efficient contract storage. |
| payable_function | Mark functions as payable (with discretion). |
| private_constant | Mark constant variables in storage as private to save gas. |
| read_storage_in_for_loop | Avoid Reading From Storage in a for loop |
| safe_math_post_080 | Identifies when SafeMath is being used if the contract using solidity >= 0.8.0. Using SafeMath when using version >= 0.8.0 is redundant and will incur additional gas costs. |
| safe_math_pre_080 | Identifies when SafeMath is being used if the contract using solidity < 0.8.0. Consider using assembly with overflow/undeflow protection for math (add, sub, mul, div) instead of SafeMath. |
| shift_math | Right shift or Left shift instead of dividing or multiplying by powers of two. |
| short_revert_string | Use revert strings that fit in one word. |
| solidity_keccak256 | Use assembly to hash instead of Solidity. |
| solidity_math | Use assembly for math (add, sub, mul, div). |
| sstore | Use assembly to write storage values. |
| string_error | Use custom errors instead of string error messages for contracts using Solidity version >= 0.8.4. |